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Proxy.handler

The proxy's handler object is a placeholder object which contains traps for proxies.

All traps are optional. If a trap has not been defined, the default behavior is to forward the operation to the target.

handler.getPrototypeOf(): A trap for Object.getPrototypeOf.
handler.setPrototypeOf(): A trap for Object.setPrototypeOf.
handler.isExtensible(): A trap for Object.isExtensible.
handler.preventExtensions(): A trap for Object.preventExtensions.
handler.getOwnPropertyDescriptor(): A trap for Object.getOwnPropertyDescriptor.
handler.defineProperty(): A trap for Object.defineProperty.
handler.has(): A trap for the in operator.
handler.get(): A trap for getting property values.
handler.set(): A trap for setting property values.
handler.deleteProperty(): A trap for the delete operator.
handler.ownKeys(): A trap for Object.getOwnPropertyNames and Object.getOwnPropertySymbols.
handler.apply(): A trap for a function call.
handler.construct(): A trap for the new operator.

Specification	Status	Comment
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Proxy Object Internal Methods and Internal Slots' in that specification.	Standard	Initial definition.
ECMAScript Latest Draft (ECMA-262) The definition of 'Proxy Object Internal Methods and Internal Slots' in that specification.	Draft	The `enumerate` handler has been removed.

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
`apply`	49	12	18	No	36	10
`construct`	49	12	18	No	36	10
`defineProperty`	49	12	18	No	36	10
`deleteProperty`	49	12	18	No	36	10
`enumerate`	No	No	37 — 47	No	No	No
`get`	49	12	18	No	36	10
`getOwnPropertyDescriptor`	49	12	18	No	36	10
`getPrototypeOf`	No	No	49	No	No	No
`has`	49	12	18	No	36	10
`isExtensible`	?	?	31	No	?	?
`ownKeys`	49	12	18 18 In Firefox 42, the implementation got updated to reflect the final ES2015 specification: The result is now checked if it is an array and if the array elements are either of type string or of type symbol. Enumerating duplicate own property names is not a failure anymore.	No	36	10
`preventExtensions`	49	12	22	No	36	10
`set`	49	12	18	No	36	10
`setPrototypeOf`	?	?	49	No	?	?

	Mobile
	Android webview	Chrome for Android	Edge Mobile	Firefox for Android	Opera for Android	iOS Safari	Samsung Internet
`apply`	49	49	Yes	18	36	10	5.0
`construct`	49	49	Yes	18	36	10	5.0
`defineProperty`	49	49	Yes	18	36	10	5.0
`deleteProperty`	49	49	Yes	18	36	10	5.0
`enumerate`	No	No	No	37 — 47	No	No	No
`get`	49	49	Yes	18	36	10	5.0
`getOwnPropertyDescriptor`	49	49	Yes	18	36	10	5.0
`getPrototypeOf`	No	No	No	49	No	No	No
`has`	49	49	Yes	18	36	10	5.0
`isExtensible`	?	?	?	31	?	?	?
`ownKeys`	49	49	Yes	18 18 In Firefox 42, the implementation got updated to reflect the final ES2015 specification: The result is now checked if it is an array and if the array elements are either of type string or of type symbol. Enumerating duplicate own property names is not a failure anymore.	36	10	5.0
`preventExtensions`	49	49	Yes	22	36	10	5.0
`set`	49	49	Yes	18	36	10	5.0
`setPrototypeOf`	?	?	?	49	?	?	?